The invention relates to a device for measuring properties of a longitudinally moved test material in a measuring cell. More particularly, the invention is concerned with means for measuring properties of yarns while such yarns are being manufactured.
In conventional yarn manufacturing practice, spinning frames and spooling frames are used to simultaneously process many yarns. Each yarn is processed while the yarn is moving in its lengthwise direction along a path at its own work station or yarn position. The several yarn positions are disposed in a row extending generally transverse to the several yarn paths.
The presently used equipment intended for measuring properties of yarn and disposed on a spinning or spooling frame, comprises three parts connected by lines, namely the measuring head with the measuring cell, the evaluation unit and the control unit. One or more evaluation units are connected to a control unit and one or more measuring heads are connected to each evaluation unit. The measuring heads supply unprocessed, analog or alternatively analog and digital signals to the evaluation unit. The evaluation unit however also supplies signals to the measuring head. The evaluation unit evaluates the signals, e.g. by comparing them with threshold values, and supplies processed and possibly also digitized signals to the control unit. Usually, one control unit per spinning frame or per spooling frame is the norm.
Such known devices take up a great deal of room. In order to take up as little room as possible in the spinning or spooling frame of the yarn, the measuring head is designed as simply as possible. It may therefore perform only a single function, namely measuring. Other functions are therefore performed in the evaluation unit. This means that such a known device comprises numerous parts, which are connected to one another by numerous lines and connectors, and its initial cost is correspondingly high. The mounting onto the spinning and spooling frame is accordingly also costly and complex. Since each measuring head is also of a specific design geared to the frame onto which it is to be mounted, this also means that, for each type of spinning or spooling frame, a special measuring head and a separate evaluation unit are manufactured.
An object of the present invention is to provide a device which is easier to adapt to the requirements of a customer and to the special conditions of a production machine for longitudinally moved test material. This object is achieved by a device, in which a measuring cell for the longitudinally moved test material is connected directly to an associated processor provided exclusively for said measuring cell. The measuring cell and the processor are permanently connected to one another and disposed on a first carrier or combined in a separate housing. In this case, there is only one output for a line for transmitting digitized signals, which have already undergone a first evaluation. Such a device may comprise a plurality of measuring cells for various tasks, which together are in turn disposed on a further carrier or in a further housing. By various tasks are meant, for example, various types of measurement, e.g., optical or capacitive measurements of the cross section or of the mass of the test material, impurity measurements, measurements of the hairiness of a yarn etc. The processor preferably takes the form of a so-called ASIC module, i.e., an application specific integrated component. It is always of an identical construction and may perform the same functions irrespective of whether it is connected to a measuring cell for optical measurement, a measuring cell for capacitive measurement etc. In particular, it is used to amplify and convert signals. For said reason, the ASIC module comprises at least one analog-to-digital converter. It therefore often has a plurality of inputs for analog signals and one output for digital signals. The further carrier comprises, besides the first carrier or carriers or housings with the measuring cells, a processor, in particular a digital signal processor (DSP), which has a plurality of inputs for connections to a plurality of ASIC modules. The first carriers with the measuring cells are connected by detachable connections, e.g., plug connectors, to the further carrier.
The advantages achieved by the device according to the invention are in particular that it is possible to dispense with a separate evaluation unit provided some distance away from the measuring head. There are therefore far fewer connections between measuring heads, evaluation units and control units of a spinning or spooling frame and so, because numerous connectors and printed-circuit boards are also dispensed with, operational reliability is increased. Since the device now comprises a low number of standardized parts, the manufacture and holding in storage of said parts by the manufacturer is likewise simplified. As larger piece numbers of each part are achieved, a greater accuracy and effort may go into the testing of said parts because specific test equipment for said purpose is worthwhile. Since the xe2x80x9cintelligencexe2x80x9d has been relocated in the measuring heads and decentralized, it is also only necessary to provide one cable from the measuring head to the production point and said cable carries digital signals, thereby making the system more fail-safe. The software is already stored in the measuring head and no longer has to be loaded there on demand.